Datasheet

123
4235K–8051–05/08
AT89C51RD2/ED2
Table 25-9. AC Parameters for a Variable Clock
25.3.8 Shift Register Timing Waveforms
25.3.9 External Clock Drive Waveforms
25.3.10 AC Testing Input/Output Waveforms
AC inputs during testing are driven at V
CC
- 0.5 for a logic “1” and 0.45V for a logic “0”. Timing
measurement are made at V
IH
min for a logic “1” and V
IL
max for a logic “0”.
Symbol Type
Standard
Clock X2 Clock
X Parameter For
-M Range Units
T
XLXL
Min 12 T 6 T ns
T
QVHX
Min 10 T - x 5 T - x 50 ns
T
XHQX
Min 2 T - x T - x 20 ns
T
XHDX
Min x x 0 ns
T
XHDV
Max 10 T - x 5 T- x 133 ns
INPUT DATA
VALIDVALID VALID VALID
0 1 2 3 4 5 6 87
ALE
CLOCK
OUTPUT DATA
WRITE to SBUF
CLEAR RI
T
XLXL
T
QVXH
T
XHQX
T
XHDV
T
XHDX
SET TI
SET RI
INSTRUCTION
0 1 2 3 4 5 6 7
VALID VALID VALID VALID
V
CC
-0.5V
0.45V
0.7V
CC
0.2V
CC
-0.1
T
CHCL
T
CLCX
T
CLCL
T
CLCH
T
CHCX
INPUT/OUTPUT
0.2 V
CC
+ 0.9
0.2 V
CC
- 0.1
V
CC
-0.5V
0.45V